Conventionally, in order to control a car, many electronic control units are incorporated in the car. As described in PTL 1, since a mechanical driving device such as an engine and a transmission, and a battery are incorporated in the limited vehicle space, the space available for the electronic control unit is limited. In order to reduce the size of the electronic control unit, the volume of components and structural members of the electronic circuit have to be reduced. When the electronic circuit is miniaturized, it is difficult to keep ground stability as the density of the plated circuit increases, and there is concern about measures against noise, and measures to suppress noise is also required.
Generally known measures against noise are to provide a low-pass filter and a small coil for constituting the filter. Examples of the small coil include a coil element as in PTL 2, in which four patterns of layers are prepared, laminated, and connected with each other through via holes to generate and laminate a coil loop, and as in PTL 3, an inductance element incorporating a coil winding and a capacitor.